The present invention is generally related to the field of the modulation of light and, more particularly, to an advanced spatial light modulator and associated methods as well its application to imaging, including but not limited to, millimeter wave imaging.
Applicants recognize that it is well known in the art to use a spatial light modulator, or SLM, in an imaging application. Frequently, the SLM used is magneto-optic, in which magnetic fields change a property of a material affecting its interaction with electromagnetic waves. One example of such materials are Faraday materials which can alter the polarization of electromagnetic waves passing therethrough, and which in response to the magnetic field in the material, can change the amount of alteration. One example of a prior art magneto-optic SLM is taught in Cox, et. al, U.S. Pat. No. 4,550,389 (hereinafter Cox) which is incorporated by reference. Cox describes an SLM suitable for imaging application as an array of magnetic domain elements, with running wires along the columns and rows. Running currents through those wires, and possibly others, can determine the magnetization of each element. Passing electromagnetic waves through such an SLM, as well as through some additional optical elements such as, for example, polarizers, allow the SLM to modulate the intensity of the light and form an image.
Applicants further recognize that published designs have attempted to apply the technique of compressive sampling and a single imaging sensor in order to achieve higher resolution than is possible with a single sensor alone. This approach has been used in cases where the imaging sensor is of a specialty type and/or comparatively expensive and it is not desirable to create an N×N matrix of imaging sensors (i.e., pixels) to generate an image with N×N resolution. In one example, millimeter wave sensors are expensive and a multi-pixel millimeter wave sensor array can cost hundreds of thousands of dollars.
Applicants still further appreciate that compressive sampling requires that a series of blocking patterns, such as, for example, Hadamard patterns, be generated. In the visible light regime, these patterns are commonly generated by solid-state spatial light modulators, such as, for example, LCDs, or nearly solid-state spatial light modulators, such as, for example, micro-mirror arrays. Additionally, millimeter wave imaging systems utilizing compressive sampling and a single-pixel sensor have been attempted. However, in these demonstrations, the series of Hadamard (or other) blocking patterns have been generated using a series of individual physical masks because solid-state spatial millimeter wave modulators are not available. In these designs, therefore, the mask must be physically moved in front of the sensor. In one embodiment, for example, a mask is placed in front of the sensor, the image captured, the mask removed, and then the next mask placed in turn, the image captured, and so forth, generating the series of images that can be used to mathematically convolve the final image.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art may become apparent to those of ordinary skill in the art upon a reading of the specification and a study of the drawings.